Supplemental Financial Information - Currency Transaction Gains (Losses) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Currency Transaction Gains (Losses) [Line Items]
Net transaction losses	$ (36,203)	$ (191,332)	$ (34,006)
Operating (loss) income
Currency Transaction Gains (Losses) [Line Items]
Net transaction losses	(29,678)	(164,042)	(25,715)
Other non-operating (expense) income, net
Currency Transaction Gains (Losses) [Line Items]
Net transaction losses	$ (6,525)	$ (27,290)	$ (8,291)

Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30700-110894

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30690-110894

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